It is well-known that a number of human disease states may be characterized by the overproduction of certain types of leukocytes, including lymphocytes, in comparison to other populations of cells which normally comprise whole blood. Excessive or abnormal lymphocyte populations result in numerous adverse effects to patients including the functional impairment of bodily organs, leukocyte mediated autoimmune diseases and leukemia related disorders many of which often ultimately result in fatality.
U.S. Pat. Nos. 4,321,919; 4,398,906; 4,428,774; and 4,464,166 to Edelson describe methods for treating blood whereby the operation or viability of certain cellular populations may be moderated thereby providing relief for these patients. In general, the methods comprise treating the blood with a dissolved photoactivatable drug, such as psoralen, which is capable of forming photoadducts with DNA in the presence of U.V. radiation. It is believed that covalent bonding results between the psoralen and the lymphocyte nucleic acid thereby effecting metabolic inhibition of the thusly treated cells. Following extracorporeal radiation, the cells are returned to the patient where they are thought to be cleared by natural processes but at an accelerated pace believed attributable to disruption of membrane integrity, alteration of DNA within the cell, or the like conditions often associated with substantial loss of cellular effectiveness or viability.
Although a number of photoactivatable compounds in the psoralen class are known, 8-methoxy psoralen is presently the compound of choice. An effective radiation for this compound, and many psoralens in general, is the ultraviolet spectrum in the range of approximately 320 to 400 naonmeters, alternatively referred to as the U.V.A. spectrum. As the development of photoactivatable compounds proceeds, it may be expected that changes in the preferred activation radiation spectrum will be necessary. Suitable selection of radiation sources will, of course, increase treatment efficiency and is contemplated as an obvious optimization procedure for use with the inventions disclosed herein.
Although Edelson's methods have been experimentally shown to provide great relief to patients suffering from leukocyte mediated diseases, nuemrous practical problems require solutions. In particular, Edelson fails to provide a suitable apparatus for applying radiation to the cells, e.g. via a treatment station, in an economical and efficacious manner, or a system for incorporating a treatment station providing for the treatment of a patient in a clinically acceptable format.
Conventional techniques for photoactivating compounds associated with cells have relied on a plurality of devices including flasks, filtration columns, spectrophotometer cuvettes, and petri dishes. The sample to be irradiated is added to the containers and the container placed adjacent to the radiation source. Such systems tend to be laboratory curiosities as they fail to provide the necessary safeguards intrinsically necessary where patient bodily fluids are concerned, particularly since these fluids must be returned to the patient thereby necessitating strict avoidance of contamination. Further, such methods tend to be volume limited, are characterized by many mechanical manipulations and are generally unacceptable from a clinical and regulatory viewpoint. It is an object of the present invention to provide methods and apparatus suitable for use with the Edelson methods to overcome the limitations associated with the conventional expedients.
Copending application U.S. Ser. No. 650,602 of Taylor describes a preferred form of a practical device for coupling the radiation provided by commercially available light sources, such as the so-called "black-light" fluorescent tubes, to cells for treatment by Edelson's photoactivated drug methods. In summary, the disposable cassette described therein comprises a plurality of fluorescent tube-like light sources such as the U.V.A. emitting Sylvania F8TS/BLB bulb, which are individually, coaxially mounted in tubes of larger diameters which are, in turn, coaxially mounted in sealing arrangement within second outer tubes of even larger diameter thereby forming a structure having two generally elongated, cylindrical cavities about each radiation source. The inner cavity preferably communicates with the atmosphere thereby facilitating cooling of the radiation source. The second tube forming the outer cavity further comprises inlet and outlet means for receiving and discharging, respectively, the cells to be irradiated. A plurality of these structures are "ganged" and suitable connections made between inlets and outlets of adjacent members to provide for serpentine flow of cells through each outer cavity. Thus, continuous flow of the cells through the plurality of cavities surrounding the centrally disposed radiation sources facilitates thorough treatment of the cells. Additional, detailed description of the Taylor device may be obtained by direct reference to U.S. Ser. No. 650,602, the relevant aspects of which are fully incorporated herein by reference.
To be fully practical, however, the Taylor device requires a clinically acceptable instrument to house the device and to provide the cells to be treated in an appropriate form. It is an object of the present invention to provide such a device.
To date and for clinical use-approval related purposes, the Edelson methods have been performed utilizing a generally impractical and unwieldy apparatus consisting of a large, desk-size metal box containing a series of flexible, relatively transparent plastic bags through which patient blood was pumped. As the blood flowed through each bag, it was irradiated on either side by a plurality of ultraviolet emitting, standard sized, "fluorescent" type tubes housed within the box. Blood flow was generated by means of a separate pump located nearby and connected to the plastic bags as well as source and drain reservoirs by flexible tubing.
Prior to treatment, it has been found preferable to perform leukocyte enriching operations for the purpose of removing substantial portions of red blood cells from the treatment circuit. With the preliminary experimental apparatus, leukocyte enrichment was obtained by centrifuging batch quantities of blood in large volume centrifuge tubes and then dispensing the supernatant plasma into the source bag for treatment. Thus, the Edelson methods have been carried out to date via a cumbersome series of labor intensive, error-prone steps, often exposing the patient's blood to numerous potential sources of contamination during its travels to and from equipment, none of which was designed to optimize the Edelson procedures. Excessive time delays and extensive mechanical manipulations were further exacerbated by the typically divergent locations of various pieces of equipment, necessitated by their space consuming construction. These considerations have resulted in lengthy treatment times and, due to the numerous physical manipulations required, have concommitantly and unacceptably increased the risk of loss or contamination of patient's blood.
It is an object of the present invention to provide methods and apparatus for increasing patient safety thereby also raising his comfort level as well as meeting regulatory acceptability standards.
It is another related object to provide a complete treatment system which contains all the elements necessary for the withdrawal, separation, and treatment of the patient's blood in a compact and clinically acceptable size and to provide the system in a mobile and automated format thereby reducing the risk of inadvertent contamination while concurrently facilitating the ease with which treatment may be given.
It is still another related object to provide a suitably automated instrument which can be monitored and operated by less trained personnel thereby lowering treatment costs in accordance with the recently enacted fiscal policies.
It is yet still another object to provide a treatment system suitable for use in the clinical arena whereby the acceptability of the Edelson procedures may be augmented so that a greater number of patients may be meaningfully treated.